I bought it of UK ebay pre weathered.... Actually I bought it to restore but started looking at it and felt it had a good even patina all over and was complete enough I thought maybe I could rat rod it and have it look right... Not for everyone I know, and frankly I could easily pull it apart and restore it correctly since I haven't changed anything. It's a great use for all those too rusty to re-use trim parts! And after working over the motor (it was stuck when I got it) it runs like a champ and pretty smooth too. Biggest problem now is locating a matching patina 263 tender to go with it.
Now to the point of how do you keep patina from going further? That I do not know. Will have to research some Jalopy Journal threads I guess. Also don't like the red paint the PO put in the sides of the boiler need to remove that.